ever since Ae 2015 13.7 Gtx 970 is supported anyway...
"The OptiX library from Nvidia is being updated on Windows, which adds the ability for Maxwell-architecture GPUs (e.g., GTX 970, GTX 980) to be used for the ray-traced 3D renderer on Windows."
just go to preferences->previews->GPU information and click "Enable untested" and enjoy.
If you look at the subject heading I'm on a Mac with OS X, not windows.
sorry about that good luck